Reliable multicast transmission with compact protocol stack

Abstract

Apparatus and methods are provided for reliable multicast transmission with compact protocol stack. In one novel aspect, compact protocol stacks are configured for the UE and the base station handling both the PTM RB and the PTP RB. The compact protocol stack is either configured a compact RLC entity or a compact PDCP entity. The UE monitors a PTM LCH and a PTP LCH and sends feedback to the network with the PTP RB. The base station transmits MBS data packets in the PTM mode to the one or more subscriber UE, monitors feedback report from each subscriber UEs through corresponding PTP RB, and retransmits MBS data packets to one or more UEs through corresponding PTP RBs based on corresponding feedback reports. PTM-to-PTP and PTP-to-PTM mode switches are performed when triggering events are detected. The mode switch notification is sent to UEs via MAC CE or RLC control PDU.

What is claimed is: 
     
       1. A method comprising:
 configuring, by a user equipment (UE), a multicast and broadcast service (MBS) with a network entity in a wireless network, wherein the MBS is configured with a point-to-multipoint (PTM) radio bearer (RB) and an associated point-to-point (PTP) RB; 
 establishing a compact UE protocol stack for data reception of MBS data packets from both the PTM RB and the associated PTP RB; 
 monitoring a PTM logical channel (LCH) for PTM data packets and a PTP LCH for PTP data packets, wherein the PTM LCH and the PTP LCH are independent; 
 assembling data packets from the PTM LCH and the PTP LCH at one UE protocol entity of the compact UE protocol stack; and 
 providing uplink feedback for MBS data reception status through the associated PTP RB using a cell radio network temporary identifier (C-RNTI). 
 
     
     
       2. The method of  claim 1 , wherein the compact UE protocol stack includes one compact radio link control (RLC) entity and one packet data convergence protocol (PDCP) entity, and wherein the compact RLC entity assembles MBS data packets received from the PTM LCH and the PTP LCH. 
     
     
       3. The method of  claim 2 , wherein sequence numbers (SNs) for RLC data packets are aligned between data packets from the PTM LCH and data packets from the PTP LCH. 
     
     
       4. The method of  claim 2 , wherein the uplink feedback is an RLC status report. 
     
     
       5. The method of  claim 1 , wherein the compact UE protocol stack includes one compact PDCP entity and two RLC entities that one for the PTM data packets and one for the PTP data packets, and wherein the compact PDCP entity assembles MBS data packets received from the PTM LCH and the PTP LCH. 
     
     
       6. The method of  claim 5 , wherein sequence numbers (SNs) for PDCP data packets are aligned between data packets from the PTM LCH and data packets from the PTP LCH. 
     
     
       7. The method of  claim 6 , wherein the uplink feedback is a PDCP status report. 
     
     
       8. The method of  claim 1 , wherein the UE monitors the PTM LCH based on a group RNTI (G-RNTI) and monitors the PTP LCH based on the C-RNTI. 
     
     
       9. A method comprising:
 configuring, by a base station, a multicast and broadcast service (MBS) for one or more subscriber user equipments (UEs) in a wireless network, wherein the MBS is configured with a point-to-multipoint (PTM) radio bearer (RB) and one or more associated point-to-point (PTP) RBs for each corresponding subscriber UE; 
 establishing a compact network protocol stack for data transmission of MBS data packets for both the PTM RB and the one or more associated PTP RBs, wherein the compact network protocol stack is configured with combination transmission mode for both the PTM RB and one or more associated PTP RBs; 
 transmitting MBS data packets in PTM mode to the one or more subscriber UEs; 
 monitoring feedback report from each subscriber UEs through corresponding associated PTP RB; and 
 retransmitting MBS data packets to one or more UE through corresponding associated PTP RBs based on corresponding feedback reports. 
 
     
     
       10. The method of  claim 9 , wherein the compact network protocol stack includes a compact RLC entity that maintains independent retransmission buffers for each corresponding subscriber UEs. 
     
     
       11. The method of  claim 9 , wherein the compact network protocol stack includes a compact PDCP entity that maintains independent retransmission buffers for each corresponding subscriber UEs. 
     
     
       12. The method of  claim 9 , further comprising:
 switching from a PTM mode to a PTP mode upon detecting one or more PTM-to-PTP triggering events, wherein transmission through the PTM RB is disabled in the PTP mode and MBS data packets are transmitted through the one or more associated PTP RBs; and 
 switching from the PTP mode to the PTM mode upon detecting one or more PTP-to-PTM triggering events. 
 
     
     
       13. The method of  claim 12 , wherein the PTM-to-PTP triggering events comprise a number of subscribers for the MBS is lower than a predefined PTM threshold, and wherein the PTP-to-PTM triggering events comprise the number of subscribers for the MBS is higher than a predefined PTP threshold. 
     
     
       14. The method of  claim 12 , wherein the base station indicates a mode switch to the one or more subscriber UEs through a control message selecting from a MAC control element (CE) and a RLC control packet data unit (PDU), and wherein the mode switch comprises a PTM mode to PTP mode switch and a PTP mode to the PTM switch. 
     
     
       15. A user equipment (UE), comprising:
 a transceiver that transmits and receives radio frequency (RF) signal in a wireless network; 
 a memory; and 
 a processor coupled to the memory, the processor configured to 
 configure a MBS with a network entity in the wireless network, wherein the MBS is configured with a point-to-multipoint (PTM) radio bearer (RB) and an associated point-to-point (PTP) RB; 
 establish a compact UE protocol stack for data reception of MBS data packets from both the PTM RB and the associated PTP RB; 
 monitor a PTM logical channel (LCH) for PTM data packets and a PTP LCH for PTP data packets, wherein the PTM LCH and the PTP LCH are independent; 
 assemble data packets from the PTM LCH and the PTP LCH at one UE protocol entity of the compact UE protocol stack; and 
 provide uplink feedback for MBS data reception status through the associated PTP RB using a cell radio network temporary identifier (C-RNTI). 
 
     
     
       16. The UE of  claim 15 , wherein the compact UE protocol stack includes one compact radio link control (RLC) entity and one packet data convergence protocol (PDCP) entity, and wherein the compact RLC entity assembles MBS data packets received from the PTM LCH and the PTP LCH. 
     
     
       17. The UE of  claim 16 , wherein the uplink feedback is a RLC status report. 
     
     
       18. The UE of  claim 15 , wherein the compact UE protocol stack includes one compact PDCP entity and two RLC entities that one for the PTM data packets and one for the PTP data packets, and wherein the compact PDCP entity assembles MBS data packets received from the PTM LCH and the PTP LCH. 
     
     
       19. The UE of  claim 18 , wherein the uplink feedback is a PDCP status report. 
     
     
       20. The UE of  claim 15 , wherein the UE monitors the PTM LCH based on a group RNTI (G-RNTI) and monitors the PTP LCH based on the C-RNTI.